SynopsisThe remote Debian host is missing a security-related update.
DescriptionA problem has been discovered in the Courier Mail Server. DNS failures were not handled properly when looking up Sender Policy Framework (SPF) records, which could allow attackers to cause memory corruption.
The default configuration on Debian has SPF checking disabled, so most machines are not vulnerable. This is explained in the 'courier' manpage, section SENDER POLICY FRAMEWORK KEYWORDS.
SolutionUpgrade the courier-mta package.
The old stable distribution (woody) is not affected by this problem.
For the stable distribution (sarge) this problem has been fixed in version 0.47-4sarge1.